Method of fixation for a mechanical dowel

ABSTRACT

An anchoring method of anchoring an anchoring element in a construction object is provided, where a surface of which object has at least one of pores in a surface, structures in a surface (such as an arrangement of ridges with undercut), a inhomogeneous characteristic with makes the penetration of a surface by a liquid under pressure possible, thereby creating pores filed by the liquid underneath the surface, and of a cavity. The method includes the steps of: providing a first element and a second element, the first element comprising a thermoplastic material; positioning the first element in a vicinity of said surface and/or of said cavity, respectively, and positioning the second element in contact with the first element; and causing a third element to vibrate while loading the first element with a force, thereby applying mechanical vibrations to the first element, and simultaneously loading the first element with a counter-force by the second element.

FIELD OF THE INVENTION

The invention is in the field of construction, especially buildingindustry, timber construction, furniture industry and mechanicalconstruction and concerns a method of anchoring an anchoring element(such as for example a dowel) in a construction object comprisingconstruction material. The invention also concerns a correspondingdevice.

BACKGROUND OF THE INVENTION

Methods of anchoring connecting elements in an opening in a fibrous orporous building material with the aid of mechanical vibrations are knownfrom publications such as WO 98/00109, WO 00/79137 and WO 2006/002569,and for example from the international patent application PCT/CH2007/000460. According to these methods a connecting element is placedin a prefabricated opening of the object or pressed against the surfaceof the object by a directed force, which in turn creates an opening.While a force acts upon the connecting element in the direction of anaxis of the opening the element is excited by mechanical vibrations. Theconnecting element comprises thermoplastic material at least on onesurface, which comes into contact with the material of the object duringthis procedure. The energy of the mechanical vibrations is set toliquefy thermoplastic material in the area of a predetermined anchoringpoint by mechanical vibrations and to press it into the pores or surfacestructures of the object by pressure building up at the anchoring pointbetween a wall of the opening and the connecting element, thus forming amost effective macroscopic anchoring.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved methodof anchoring an anchoring element. The term “anchoring element” used inthis text refers to any element that is suitable of being anchored andforming or being part of, after anchoring, an anchor. Such anchorsinclude but are not restricted to connecting elements, such as a dowels,rivets, nails, etc. or any other piece to be anchored directly in theobject. Anchors in this sense are suitable of attaching a further partto the construction object, or they may in themselves have a function,for example for decoration.

It is a further object of the invention to provide an anchoring methodsuitable of automation, where possibly the working parameters (forces,energies etc.) can be pre-defined.

It is yet a further object of the invention to provide an improvedanchoring device.

The construction object, in which the anchoring element may be anchored,may as a first option have a porous or structured surface or surface inwhich pores can be generated by a liquid under hydrostatic pressure. Theobject may then be of wood, a wood composite (such as chipboard,particle board, oriented strand board etc), cardboard, concrete, brick,plaster, stone (such as sandstone) or industrial hard foam, into which aliquefied material can penetrate under pressure, or a composite of anycombination of the mentioned materials. As a second option, the objectmay have a cavity into which liquefied material can get during theanchoring process to thereby anchor the anchoring element. According tothis second option, a material of the construction object may be of anyone of the materials mentioned for the first option, or of any otherconstruction/engineering material, including, but not limited to,metals, such as steel, aluminum etc. The object may correspond to both,the first and the second option.

According to the invention, therefore, an anchoring method of anchoringan anchoring element in a construction object is provided, where asurface of which object has at least one of:

-   pores in a surface-   structures in a surface (such as an arrangement of ridges with    undercut)-   a inhomogeneous characteristic with makes the penetration of a    surface by a liquid under pressure possible, thereby creating pores    filled by the liquid underneath the surface (the creation of pores    in hard material such as wood is caused by the local breaking of    connections, such as between wood fibres, whereas the creation of    pores in softer material such as core material (‘isolation    material’, etc. may be due to the local displacement and/or    compression of the softer material); and-   a cavity;

the method comprising the steps of

-   providing a first element and a second element, the first element    comprising a thermoplastic material;-   positioning the first element in a vicinity of said surface and/or    of said cavity, respectively, and positioning the second element in    contact with the first element;-   causing a third element to vibrate while loading the first element    with a force, thereby applying mechanical vibrations to the first    element, and simultaneously loading the first element with a    counter-force by the second element;-   by the joint application of the mechanical vibrations and the load,    liquefying at least some of the thermoplastic material at at least    one interface, thereby creating liquefied material, wherein said at    least one interface is at least one of an interface between the    first element and the third element, of an interface between the    first element and the second element, and of an interface between    parts of the first element;-   causing, by the joint application of the mechanical vibrations and    the load from by the second and third element, the first element to    be compressed and thereby causing the liquefied material to flow    into pores and/or structures and/or the cavity; and-   letting the liquefied material re-solidify so that the first element    is anchored in the object.

The first element comprises the thermoplastic material and is compressedduring anchoring while at least some of the thermoplastic material isliquefied. Usually, by the compression between the force and the counterforce, the liquefied material is caused to flow sideways with respect toan axis defined by the force, i.e. at least partially into lateraldirections. For example, the liquefied material may be caused to flow inall lateral directions to substantially form a ring surrounding theinitial position of the anchoring element.

The compression of the first element in the method according to theinvention is made possible by the liquefaction of thermoplasticmaterial, and the compression causes the liquefied material to evade(usually sideways) into the structures/pores/cavity. The first elementin its solid state need not be compressible (and preferably is notcompressible) along the axis defined by the bore or opening direction.This is in contrast to the teaching of PCT/CH 2007/000460, whereliquefaction is based on contact with the material surface, whichcontact is caused by a compression that causes a lateral distance of anoutermost surface to the axis to be increased, in the solid state.Preferably, the anchoring element does, in its solid state, does notexhibit any substantial compression under ‘normal’ conditions (i.e. whenforces of the magnitudes used during anchoring impinge at atmosphericconditions). This means for example, that a small residual compression(any element has some elasticity and is in theory, to some very smallextent, compressible) is essentially angle preserving (deforms theanchoring element in a conformal manner), the angle deformations forexample not exceeding 3°, and the compression under normal circumstancesdoes not exceed 3%.

The first element is also denoted anchoring element in this text. Thisdoes not imply that the anchor necessarily consists of the anchoringelement only; the anchor may comprise further elements, including,optionally, the third and/or the second element.

The second element may be any dimensionally stable element suitable ofapplying a counter force to the first element. It may be of one piece orit may comprise a plurality of parts connected to each other or restingagainst each other during the anchoring process. The second element maybe of a material not liquefiable by the mechanical vibrations—such asmetal, a thermosetting plastics or a thermoplastic material with asubstantially higher glass transition temperature than the thermoplasticmaterial of the first element. As an alternative, the second element maycomprise liquefiable material (however, in most cases liquefaction ofsuch material will only occur indirectly by heat or vibrationtransmission through the first element, the second element preferablybeing vibratory decoupled from the third element with the exception ofthe path through the first element).

Whereas in most preferred embodiments, the second element will be heldstill (and only vibrate by weakly being vibratory coupled to the thirdelement through the first element), this need not be the case. Rather,the second element may also be actively caused to vibrate, thevibrations being different from the vibrations of the third element (andfor example of opposite or different phase and/or a different frequencyetc.)

The third element as a whole is suitable of transmitting the mechanicalvibrations from a mechanical vibration generator (that may include apiezoelectric transducer; more in general mechanical vibrationgenerators are known in the art and will not be described in any moredetail here) to a contact face with the first element. To this end, thethird element is preferably designed so that at the vibrating frequency,it oscillates so that the interface where the vibrations are to becoupled into the first element should be at a place of maximum amplitudeor close thereto. If, for example the third element is of one piece ofmaterial and has a substantially constant cross section, the vibrationsare longitudinal vibrations, and the wavelength of the vibrations of thevibration frequency is λ, the length of the third element is preferablyapproximately n*λ/2, where n is any natural number.

The third element may be a one-piece element or comprise a plurality ofpieces that are rigidly fixed to each other (e.g. by a positive-fitconnection such as screwing, by welding, or by gluing).

The vibrations in the third element may be longitudinal vibrations,transversal vibrations, torsional vibrations, other kinds of vibrations,or combinations (superpositions) of different vibration modes.

In contrast to the methods described in WO 98/00109, WO 00/79137 and WO2006/002569, and in the international patent application PCT/CH2007/000460, the method according to the invention is based on aliquefaction of the thermoplastic material by way of (external orinternal) friction forces at at least one interface between the first,second and/or third element (or parts thereof) an/or at at least oneinterface within the first element. This leads away from thestate-of-the art concept of liquefying the thermoplastic material byfriction between the anchoring element and the object surface. Instead,the material is liquefied at interfaces between initially separate (oronly weakly coupled) elements or within the elements themselves. Inother words, the elements involved in the method are arranged in amanner that the thermoplastic material would melt even in the absence ofthe object in which the anchoring element has to be anchored, purely bythe joint action of the forces applied to the first element through thesecond and third element and the mechanical vibrations. This makes theapplication of the necessary forces in a pre-defined manner possible.Automation of the process as a consequence is possible more easily, forexample by having the necessary forces applied within a load frame andwithout external forces onto said load frame.

The melted thermoplastic material is then caused to flow intopores/structures and/or at least one cavity. This may necessitatehydrostatic pressure to build up (due to the effect of the compressionof the anchoring element). However, almost no or only little hydrostaticpressure is necessary in case the object is already porous or in case itis (locally) of a weak material. As a consequence precisely in the caseswhere the object could easily be damaged by the impact of forces actingon it, the possibly only impact on the material is a very smallhydrostatic pressure.

For an anchoring element of constant (as a function of the positionalong the axis) cross section, the interface to the vibrating thirdelement is automatically the default place for the liquefying to start,and this is desired in many embodiments of the invention. However, theanchoring element may also—deviating from the constant crosssection—comprise an energy director (energy concentrator) or a pluralityof energy directors to ensure that the liquefaction takes place at thedesired location.

Such energy directors may be structural energy directors, such as atleast one of

-   a reduction of a cross section as a function of the position along    an axis, towards the interface where liquefaction is desired,-   at least one protrusion within a broad ranges of diameters, the    protrusion being at the interface where liquefaction is desired,

Energy directors may, however, in addition or as an alternative, also bedue to material properties. They thus may comprise:

-   an inhomogeneous material distribution over the anchoring element    (and/or the second and/or the third element), so that the material    adjacent the interface where liquefaction is desired has a higher    absorption for mechanical vibration energy than material adjacent an    other interface (for example the opposite interface). For example    the anchoring element may comprise two parts adhering to each other,    the part adjacent the interface to the third element being softer    than the part adjacent the interface to the second element (or vice    versa). As an other example, the anchoring element may comprise a    softener with a concentration gradient over the anchoring element's    length, etc.

The anchoring element may for example comprise a first and a secondcoupling face, different from the first coupling face, where the forceis caused to impinge on the anchoring element by pressing the thirdelement against the first coupling face, and where the counter-force iscaused to impinge on the anchoring element by pressing the secondelement against the second coupling face.

The coupling faces may for example be on opposite sides of the anchoringelement. They may be substantially perpendicular to or at an angle tothe axis defined by the direction of the force. They can optionally besubstantially parallel to each other.

The force and the counter force are preferably equal in magnitude buthave opposite directions. This condition, however, has to be fulfilledonly approximately, as the anchoring element may for example contact,during anchoring, a sidewall of the object and thereby absorb a furtherforce compensating for minor inequalities of magnitude and/or directionof the force and counter force.

The force and the counter force, however, are such that during anchoringthe surface comprising the pores/structures/inhomogeneouscharacteristic/cavity does not need to be mechanically loaded. Allprocesses leading to the liquefaction of at least a part of thethermoplastic material and to the pressing out of the liquefiedmaterials (that will then be caused to flow into pores or structures orthe cavity) are independent of the object in which the anchoring elementis anchored. As mentioned, the liquefaction of the thermoplasticmaterial would also work absent the object—even in vacuum or underwater.

Whereas this liquefaction independent of a contact to the constructionobject is, according to the invention, the predominant liquefactionmechanism, this does not exclude additional melting by friction betweenthe anchoring element and the object.

The approach according to the invention has major advantages:

-   Suitability for Automation: Since the necessary parameters for a    given assembly of the first, second and third element are known, the    required forces may be applied automatically, and even with an    apparatus for which no feedback on resistance forces etc. is    available. The geometrical details of the construction object are    irrelevant. The material properties of the construction object are    only relevant to the extent that the hydrostatic pressure used for    causing the liquefied material to flow into pores may depend on the    material properties. This may be taken care of by providing the    possibility of applying material dependent forces (that can easily    be chosen between), or by ensuring that the force and counter force    are in any case sufficient also for interpenetration of comparably    hard structures.-   Independence from the Geometry of the Construction Object: The    parameters (forces to be applied; vibration energies etc.) only    depend on the elements used and not on the construction object.

Independence from the Construction Material Quality: Since no frictionis required between the thermoplastic material to be liquefied and theobject in which the anchoring element is anchored, the anchoring maytake place also in material that is very weak and/or brittle, such ashighly porous material (plasterboard, cardboard, low quality woodcomposites, diluted foams etc.).

-   New Degrees of Freedom Concerning Materials: Due to the approach    according to the invention, it is not necessary any more to    transport vibration energy through the thermoplastic material from a    coupling-in face to a place where the thermoplastic material is in    contact with the object it is anchored in. Rather, the liquefaction    may take place directly at the interface between the first and third    elements, within the first element (due to internal friction) or at    other interfaces. Due to this, the vibration energy transportation    capabilities of the thermoplastic material are less important than    in prior art methods, and consequently the skilled person, if    confronted with a specific task, can choose between more materials.

Automated anchoring may for example be useful in a manufacturing line offurniture or of pre-fabricated building elements or other objects. Itmay also be used in a handheld device, for example to be utilized by aprofessional or do-it-yourselfer in building. Depending on theimplementation, an automated device does not need to be pressed againstthe object any more, but all forces may be created within a load frameof the automated device. If many anchors are set, the process is thusless exhausting for the user. Also, the anchoring will be successfulindependent of the knowledge the user has of the object and of theuser's skills.

A preferred variant of any one of the herein described embodiments,therefore, features the step of automatically applying, by means of aspring element, a hydraulic or pneumatic element or an other suitablemechanism, the force acting on the anchoring element during anchoring.For example, the spring element/hydraulic element/pneumatic element maybe arranged so as to exert a well-defined force between a non-vibratingpart of the vibration generator (and thus indirectly the third element)and the counter element.

Preferably, the anchoring element is anchored in a pre-fabricatedopening (blind hole or through hole). The flowing of the liquefiedmaterial into lateral directions may then cause the liquefied materialto penetrate pores and/or structures of the lateral side walls of theopening. In addition or as an alternative, the anchoring takes place bymeans of a cavity behind (on the rear side of) a pre-fabricated bore.Such a cavity may have an unlimited width or a larger diameter than thepre-fabricated bore, measured perpendicularly to the axis.

“Pre-fabricated” does not imply that a bore necessarily has to be madefor the purpose of the anchoring only; rather, any already presentopening or space may be used for anchoring also.

In this text, the orientation of the elements is sometimes describedreferring to an axis, which axis (“anchoring axis”) is defined by thedirection of the forces applied during the anchoring process. In theembodiment, in which the anchoring element is anchored in apre-fabricated bore, the axis is often coaxial with an axis of the bore.Often, the person or apparatus carrying out the method according to theinvention has or needs access to the element to be anchored and thetools from one side only (often, for example, if the anchoring elementserves as a “dowel” or fastening nail or fastening screw). The side fromwhich the person or apparatus carrying out the method accesses thetool(s)—the “front” side—is referred to as the “fore” side, whereas theopposite side of the elements—the side protruding the deepest into theobject or reaching the rear side—is termed the “rear” side in this text.The “forward” direction regarding the driving an element into theconstruction object is the direction away from the user or apparatus(the “ordinary” direction for example for driving a nail or dowel intoan object) and “backward” denotes the opposite direction towards theuser.

According to a special preferred principle, the force is coupled intothe third element—that may be a sonotrode—as a pulling (tensile force).According to this special preferred embodiment of the invention, themechanical vibrations may be coupled into the first element (anchoringelement) from the rear side. This means that the third element—that mayfor example be a sonotrode of a vibration generating device—reachesthrough the first element and accesses the first element from behind, sothat the first coupling face of the first element is in contact with acoupling section of the third element.

This special preferred principle features substantial advantages overthe prior art. In the anchoring method according to the state of the artas for example disclosed in WO 98/00109, the mechanical vibration energyused for melting the thermoplastic material is applied from the foreside and has to be transferred through the anchoring element to the rearside, where the material is to melt in contact with the constructionmaterial and to anchor therein. This can cause problems in connectionwith the coupling of the sonotrode to the anchoring element, as the foreend of the anchoring element may be activated, and the vibration energyis absorbed at the fore end instead of being transferred to the rear end(“head melting” of the anchoring element). The overcoming of this effectnecessitates, among other things, the force between the sonotrode andthe anchoring element to be comparably large, so that the connectionbetween them is strong. The approach according to the special embodimentof the invention, in contrast, transfers the mechanical vibration energyto the rear end of the anchoring element—where the latter is supposed tomelt—directly by the not liquefiable third element (the “sonotrode”/the“tool”), and the “head melting” effect is utilized. Also, the melting ofthe thermoplastic material occurs at the desired places without the needof a strong force to be applied.

In order to be able to access the anchoring element from the rear side,the sonotrode is usually long and narrow enough to reach through theanchoring element—or alongside it—to its rear end. Preferably theanchoring element is hollow (thus for example tube shaped or sleeveshaped), a shaft of the sonotrode reaching through the axial throughhole of the anchoring element. The anchoring element can be one part orcomprise a plurality of parts, each having an axial through opening.

If the anchoring element (consisting of one piece or of several parts)has an axial through opening through which a shaft of the sonotrodereaches, the sonotrode—or a part attached to it for transferring themechanical vibrations—has to have a rear broadening so that anoutward-facing outcoupling face is formed, the outcoupling face to bebrought in contact with the first coupling face of the anchoringelement. After anchoring, however, such a rear broadening cannot beremoved to the fore side any more, because of the anchoring element.Therefore, there are the following basic possibilities to proceed.

-   The rear broadening together with the shaft remains in place after    anchoring and forms part of the anchor. For example, the rear    broadening and the shaft may be one-piece (and for example metallic)    and together form the sonotrode. This possibility is especially    advantageous if the shaft is to be used to attach a further element.    To this end, the shaft may optionally comprise structures such as a    threading or elements of an other kind of fitting.-   The rear broadening and the shaft may be separated from each other    after anchoring. In this case, the rear broadening is formed by a    base element, preferably of a different material than the shaft. For    example, the rear broadening may be made of a thermoplastic material    fit to a rear end of the shaft, which shaft may for example be    metallic. The thermoplastic material may be the same as the one of    the anchoring element, or it may be different. Due to a softening or    melting of the thermoplastic material during or after the anchoring    process, the shaft may be retracted. In accordance with this second    possibility, the base element may be welded to the anchoring element    during anchoring and forms part of the anchor after anchoring. As an    alternative, the shaft and the base element may both be made of    material that does not melt under the anchoring conditions (for    example, they both may be made of a same material), and may be    connected together with a mechanical locking (such as a threaded    connection or a bayonet fixing) that may be released after    anchoring.-   The sonotrode can be removed towards the rear side. For practical    reasons, this is most often not an option, however.

In embodiments according to the special preferred principle, there aredifferent possibilities of compressing the anchoring element between thetwo coupling faces. If the anchoring element comprises two couplingfaces on opposite sides thereof, the most general description is thatthe second and third element are moved relative to each other so thatthe anchoring element is compressed between the coupling faces (thecoupling faces approach each other).

According to a first variant, the second element (often named “counterelement” in this text) is kept still relative to the constructionobject. The second element may for example comprise a surface portionresting against a front surface of the construction object. The thirdelement (the sonotrode, possibly including an element connected to thesonotrode) is then pulled towards the front side to compress theanchoring element.

According to a second variant, the third, vibrating element is kept at afixed position, and the second element is pushed towards the rear sideto compress the anchoring element. This second variant is especiallyadvantageous in cases where the depth of the opening in the constructionobject is limited. For example, the anchoring element may initially belonger than the depth of the opening.

The force by an element kept at a fixed position does not produce anywork in the physical sense. It thus does not need not be an active forcebut can be caused by the respective element—or a part affixed to it—ismerely supported by a dimensionally stiff item that is not movablerelative to the object—such as a foremost surface of the object itself.In the case of the second variant, of course, it is not the thirdelement itself element that is supported by the unmovable item but anon-vibrating casing of the vibration generator, or a non-vibrating partaffixed to the vibration generator.

Also hybrids between the first and second variant are possible, i.e.methods in which both, the second and the third element are movedrelative to the construction object.

According to an alternative to the “tensile force” or “rearward”principle, in a different embodiment of the invention, the mechanicalvibrations are applied, conventionally, from the fore side, whereas thecounter force is applied from the rear side by the second element. Thesecond element can then be such that it reaches to the front objectsurface and can be held from there—either by propping on the objectfront surface or by the person or apparatus applying the method. This ispreferred in situations, where the bore in the construction object iseither a through bore or where the construction material at the base ofthe bore is relatively weak or brittle.

As an alternative for stronger construction objects, other embodimentsof the “forward” anchoring principle may feature the counter elementresting against the base of the bore during the anchoring process.

The counter element may for example be a receptacle formed by a sleevewith a plurality of holes and a receptacle mouth, the first elementbeing placed within the receptacle. During liquefaction, the liquefiedmaterial is pressed through the openings and into pores, structures,and/or the cavity of the construction object. The counter element maycomprise a flange protruding sideways in the region of the mouth, sothat the counter element may prop on a stable front surface of theconstruction object. As an alternative, the sleeve may be anchored in acounter sunk manner, the sleeve resting against the base of the bore inthe construction object during anchoring.

The embodiments where the counter element is a sleeve with a pluralityof holes have the additional—sometimes advantageous—feature that theflow of the liquefied material is spatially restricted. It takes placeonly at characteristic outflow (opening) locations that moreover mayremain at a fixed location during anchoring.

In this text “thermoplastic material” is used for describing a materialcomprising at least one thermoplastic component able to be liquefied bymechanical vibrations due to external and/or internal friction. Thethermoplastic material makes up at least a part of the anchoringelement; it may form the whole anchoring element. Besides thermoplasticsthe thermoplastic material can also comprise non-thermoplasticcomponents, such as reinforcing fibers, reinforcing splints, fillingmaterials etc. Non-thermoplastic components can be evenly distributed inthe thermoplastic material or be present in varying concentrations. Theanchoring element can further comprise areas free of thermoplasticmaterial. Such areas may be of metal, glass, ceramic material, or ofnon-thermoplastic materials or thermoplastic material(s) liquefiable atsubstantially higher temperatures compared to the basic thermoplasticmaterial.

The mechanical frequency of the mechanical vibrations—this too appliesto all aspects of the invention described in this text—often liesbetween 2 kHz and 200 kHz and their amplitudes may be around 20 μm, i.e.between 1 μm and 100 μm—for special applications also higher or lower.If the thermoplastic material is to take over a load hearing functionand is to liquefy only in the named contact areas, it ought to have acoefficient of elasticity of more than 0.5 GPa, preferably 1 GPa orhigher. However, as mentioned elsewhere in this text, the inventionmakes possible that new classes of thermoplastic materials may be usedfor anchoring, including thermoplastic materials with a comparably lowmodulus of elasticity, in special applications even less than 1 GPa orless than 0.5 GPa.

Any thermoplastic material or combination of thermoplastic materialsused in construction can be applied. Examples of thermoplastic materialsinclude a wide variety of harder and softer polymer materials, includingtheir copolymers and their blends. In fact, almost any polymer that canbe injection molded may be used. A table of suitable materials can forexample be found in “Plastics and Composites Welding Handbook”; GrewellD. A., Benatar A., Park J. B (eds.) Hanser Publishers, Munich, 2003, pp.176-179.

The invention also concerns a device for producing an anchor in aconstruction material object. The device is preferably designed forcarrying out the above-described method and comprises the elementsmentioned in the description of the method. The device may for examplecomprise

-   an anchoring element comprising thermoplastic material and    comprising a first and a second coupling face,-   a counter element comprising a counter element coupling face,-   and a third element, the third element being suitable of being    coupled to a generator of mechanical vibrations and of transferring    the mechanical vibrations to an outcoupling face of the third    element,-   the anchoring element, the counter element and the third element    adapted to be assembled so that:-   the outcoupling face of the third element abuts the first coupling    face; and-   the counter element coupling face abuts the second coupling face,    and-   a compressing force can be applied onto the anchoring element by    loading the third element and the counter element with a force and a    counter force, respectively, of equal magnitude and opposite    directions;-   wherein the directions of the force and the counter force are such    that, with respect to an axis defined by the force and the counter    force, a lateral outermost surface of the anchoring element in    vicinity to an interface to the third element is formed by the    thermoplastic material.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, embodiments of the invention are described inconnection drawings. The drawings are schematical and not to scale. Inthe drawings, same reference numerals are used for same or equivalentelements. Therein:

FIGS. 1 a and 1 b illustrate a first embodiment of the device and methodaccording to the invention;

FIG. 2 shows a variant of the device of FIGS. 1 a and 1 b;

FIG. 3 depicts an alternative principle of a method and device accordingto the invention;

FIG. 4 illustrates an assembly, including a device according to theinvention, to carry out an embodiment of the method according to theinvention;

FIGS. 5 a-5 e show method steps of an embodiment of the method accordingto the invention;

FIGS. 6 a and 6 b illustrate yet a further embodiment of a method anddevice according to the invention;

FIGS. 7 a and 7 b illustrate an even further embodiment of a method anddevice according to the invention;

FIGS. 8 a and 8 b show yet another embodiment of a method and deviceaccording to the invention;

FIGS. 9 a-9 e illustrate method steps of a further embodiment of themethod according to the invention;

FIGS. 10 a and 10 b show an embodiment of a method and device accordingto the invention applied for anchoring in a hollow core board;

FIGS. 11 a and 11 b depict an embodiment of a method and deviceaccording to the invention applied for anchoring at a hollow wall;

FIGS. 12 a and 12 b show an embodiment of a method and device accordingto the invention applied for anchoring in vertically perforated brick;

FIGS. 13 a-13 c illustrate variants of anchoring elements and sonotrodeshafts in section;

FIG. 14 shows a coupling suitable for transmission of a pulling force;

FIG. 15 illustrate yet another embodiment of a method and deviceaccording to the invention;

FIGS. 16 and 17 show top views of sonotrodes according to variants ofseveral embodiments of the invention;

FIG. 18 illustrates, in sectional view, an other arrangement of ananchoring element and a counter element for “forward” anchoring;

FIGS. 19 a and 19 b depict an embodiment of a method and deviceaccording to the invention;

FIGS. 20 a and 20 b show a further embodiment of a method and deviceaccording to the invention; and

FIG. 21 shows a variant of an arrangement for different embodiments ofthe invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The first element (anchoring element 1) of FIG. 1 a is formed by asleeve of a thermoplastic material with a sleeve axis 7. The end facesof the anchoring element 1 define a first and a second coupling face1.11, 1.12.

The anchoring element in the illustrated configuration is located in abore of the construction object 11. With respect to an axial direction,it is sandwiched between a second element (counter element 2) and anoutcoupling face 3.1 of a third element (tool 3). To this end, the tool3 comprises a tool shaft 3.4 and a rear broadening 3.2 that in theillustrated version is disk-like and defines the forward facingoutcoupling face 3.1.

In the anchoring process, a pulling force is applied onto the tool 3,and at the same time a counter force of the same magnitude but of anopposite direction is applied onto the counter element, so that theanchoring element 1 is compressed between the tool and the counterelement. In the shown configuration, the counter element rests againstthe front surface 11.1 of the object 11, so that the force externallyapplied to the counter element 2 does not need to be precisely definedbut can be larger than the pulling force, as the normal force from theobject 11 onto the counter element 2 compensates a possible surplus ofthe external force and in this situation automatically adjusts thecounter force to be equal in magnitude to the pulling force.

In this and the following figures, the force applied to the vibratingelement (and from the vibrating element onto the anchoring element) isgenerally symbolised by an arrow 4, whereas the counter force beingapplied by the counter element is represented by a dotted arrow 6,irrespective of whether the respective force is a holding force (i.e.the element upon which it acts is held still by it) or whether itactually moves the element to compress the anchoring element. In fact,as illustrated further below, the force applied onto the tool, or theforce applied onto the counter element, or both, the force on the tooland the force on the counter element may cause the respective element tomove and thereby to compress the anchoring element between the tool andthe counter element.

While the pulling force acts on the tool 3, mechanical vibrations—suchas ultrasonic vibrations, the vibrating frequency for example beingbetween 2 kHz and 200 kHz—act on the tool. Thereby, the thermoplasticmaterial at first coupling face 1.11 starts melting. The anchoringelement 1 towards its rear and comprises a taper 1.21 serving as energydirector.

Due to the pulling force, the liquefied thermoplastic material is causedto flow sideways into pores or pre-existing structures of theconstruction object or to penetrate into inhomogeneities of theconstruction object material (thereby creating and filled pores in it).This is illustrated in FIG. 1 b. The pressure by which the liquefiedmaterial portions are pressed into pre-existing pores or inhomogeneitiesmay be influenced by the tool shape. For example, if the rear broadening3.2 is such as to cover the full width of the bore, liquid material maynot flow rearward, so that the pressure may be higher than if liquidmaterial could evade to the rear side.

The portions 1.22 of the liquefied material pressed into the pores afterre-solidification define a form-fit connection that due to its deepanchoring in the construction object is sound also if the constructionobject material is comparably soft or brittle and/or has substantialinhomogeneities.

In the shown configuration, the tool 3 after the anchoring processcannot be removed any more. The tool, however, may serve as functionalpart of the anchoring element, and for example be used for affixing afurther element to it. It may for example comprise a threading (notshown) or other structure enabling such connection, or the other elementmay be glued or soldered or welded etc. to it. The rear broadening ofthe tool may moreover, as an alternative to the above-mentionedembodiment, be such that it does not have the full width of the bore, sothat some liquefied material may also flow behind the broadening sothat, after anchoring, there is a form-fit connection between the tool 3and the anchoring element 1, too.

In an alternative version, the bore may be a through hole, and the toolmay be removed towards the rear side. Possibilities of having the toolremoved from the fore side are illustrated further below.

The embodiment of FIG. 2 is distinct from the one of FIGS. 1 a and 1 bin that the sleeve-like anchoring element 1 is comparably thin-walledand does not have any energy directors.

FIG. 3 shows the anchoring element in a through hole. The shownconfiguration is also distinct from the configurations of FIGS. 1 a and2 in that the tool 3 (sonotrode) is not pulled during the anchoringprocess but pushed. In the depicted version, the sonotrode is tubeshaped. The counter element on the other hand has a shaft 2.4 reachingthrough the anchoring element and further has a rear broadening forbeing pressed against the second coupling face 1.12 of the anchoringelement. The counter element may remain in place after anchoring, or itmay be removed from the rear side if such removal is possible.

An other feature of special embodiments of the invention is alsoillustrated in FIG. 3. Depending on the shape of the anchoring element,the anchoring element 1 may be caused to start melting at the interfaceto the counter element 2, too, or even only at that interface (and notat the interface to the sonotrode). In FIG. 3, the anchoring elementcomprises a first taper towards the sonotrode, and a second, moreprominent taper towards the counter element. Depending on taper (or itsabsence), the chosen modulus of elasticity of the thermoplastic materialand on the wavelength of the mechanical vibrations in the anchoringelement 1, the thermoplastic material may be caused to start liquefyingat the interface to the sonotrode or to the counter element or evenboth. In the configuration illustrated in FIG. 3, the thermoplasticmaterial may start being liquefied at both interfaces. Suchconfigurations (both, of the “foreward” and of the “rearward” type) maybe used to assure a controlled two-position anchoring. This can be thecase within a single opening in the construction object in order toenhance stability. As an alternative, this could even be the case in twodifferent construction objects (thus the rear side anchoring position isin one object, and the fore side anchoring position in the other object,this anchoring securing the two objects against each other).

A special advantage of the approach according to the invention, however,is that it is especially suited for the case where the anchoring elementstarts melting at the interface to the sonotrode (or other vibratingelement). Therefore, in all figures (except in FIG. 3 and whereexplicitly mentioned to be otherwise) the situation is illustrated wherethe liquefying (initially) takes place at the interface to the vibratingelement. The skilled person will, however, recognize that based on theteaching of FIG. 3 it would also be possible to modify the configurationof other figures to enable initial melting at other places, too.

FIG. 4 illustrates the principle of a base element 31 that is used forapplying the vibrations and that allows removal of the sonotrode afteranchoring of the anchoring element. The base element is coupled to thesonotrode 3 before anchoring. This can be done for example by athreading of the sonotrode 3 and the base element 31 or by the sonotrodehaving appropriate structures (such as ribs/grooves 3.11, as illustratedin FIG. 4, a surface roughness, etc.), and causing thermoplasticmaterial of the base element, in an assembly step, to be locallyliquefied and to flow into these structures.

More in general, the assembly of the elements needed for the anchoringprocess includes the steps of:

-   Soundly coupling the sonotrode 3 to the vibration generating device    32. The corresponding coupling means 33 is schematically illustrated    in FIG. 4;-   Pushing the counter element 2 and the sleeve like anchoring element    1 onto the sonotrode 3; and-   Coupling the base 31 element to the rear end (tip) of the sonotrode    3. If this is done by local or full melting of base element 31    material, the base element 31 (or base element material) may, during    this, be held by an appropriate device. Such device may even be    formed as a mold for the base element, so that the base element need    not be pre-fabricated but can be manufactured by casting liquid    thermoplastic material into the mold. As an alternative thereto, the    base element may be pre-fabricated, and the sonotrode may be pressed    into while it vibrates.

Thereafter (if necessary after cooling of the base element), theassembly may be placed in an appropriate pre-fabricated opening in theconstruction object. This opening (bore) is made with a slightly largerdiameter than the outer diameter of the base element and the anchoringelement. The opening may be a through opening or a blind hole and in thelatter case may be slightly deeper than the length of the anchoringelement.

Then, the sonotrode with base element and anchoring element is insertedinto the opening and brought into the desired position.

The anchoring process itself is illustrated in FIGS. 5 a through 5 e.FIG. 5 a illustrates the step of inserting the sonotrode with theanchoring element and the base element in the opening. When theanchoring element has reached its position (FIG. 5 b), the counterelement is pressed against the front surface 11.1 of the object (arrow6), and the mechanical vibrations start (arrow 5). Then, while themechanical vibrations and the counterforce continue to be active, thesonotrode is retracted by a pulling force, causing the materialliquefied by the joint action of the pulling force and the mechanicalvibrations to penetrate lateral walls of the bore of the constructionobject (FIG. 5 c). In this process, the thermoplastic materialsurrounding the sonotrode is also softened, and after a certain time,the sonotrode may be retracted as illustrated in FIG. 5 d. Afterretraction of the sonotrode 3 and removal of the counter element 2, theanchoring element and the base element together remain anchored in theobject 11. Since the thermoplastic material has melted at the interface,the anchoring element 1 and the base element 31 will be welded together,together forming, after re-solidification, an anchor 41 that may forexample serve as a dowel for affixing a further object (FIG. 5 e).

This “dowel” utilization—also anchors made by other embodiments of themethod according to the invention may be used as dowels—is especiallysuited for affixing screws to weak or locally weak construction objects,such as objects of porous concrete (as illustrated) or other weak, softor brittle materials.

In FIG. 6 a and FIG. 6 b, additional principles are shown. Theseprinciples need not be combined as shown in the figures, but can ratheralso be applied separately, and, where compatible, in combination withprinciples referred to in other figures, such as in combination with thesonotrode arrangements of FIGS. 1-3:

-   The anchoring element comprises two initially separate anchoring    element parts 1.1, 1.2 that may be both of the same thermoplastic    materials or may be made of different materials. For example, the    second anchoring element part 1.2—the one that is not in direct    contact with the vibrating element—may be made of a thermoplastic    material with a higher glass transition temperature than the first    anchoring element part 1.1 or of a not thermoplastic material.    During the anchoring process, the first anchoring element part 1.1    melts, starting from the first contact face 1.11 (the contact face    to the vibrating element) to an extent that also thermoplastic    material in contact with the second anchoring element part 1.2 is    melted and the anchoring element parts are welded together.-   The counter element is not disk-like or plate like with a central    through opening, as shown in the previous figures, but comprises a    flange like collar capable of protruding into the opening and thus    making possible that the anchoring element is not flush with the    object front surface but countersunk. Other shapes of the counter    element—defining diverse anchoring element positions, including    positions where the anchoring element protrudes from the    construction object front surface—are possible.

In the shown configuration, the thermoplastic base element of theanchoring element, as described referring to FIGS. 4 and 5 a-5 e isduring the anchoring process, also welded to the anchoring element andthus may be viewed as a further part (a third part in the illustratedembodiment) of the anchor 41.

The anchor, after removal of the sonotrode 3, serves as a dowel for ascrew 22 that may be screwed into the thermoplastic material after there-solidification step. The screw may for example be used to affix afurther element 23—illustrated only very schematically in the Figure—tothe object 11.

Further variations may include

-   The second element (counter element) 2 need not be made of a metal,    but may be made of a plastics, for example of a thermoplastic    material the glass transition temperature is well above the glass    transition temperature of the anchoring element 1 itself, or of a    thermosetting material;-   Between the second element and the place where the person or    apparatus applies the counter force , a further element may be    arranged. In fact, any number of number of elements (including    washers, sleeves, sockets etc.) may be present.-   The anchoring element or its foremost (closest to the user or    apparatus carrying out the method) anchoring element part may    comprise an anchoring element head for directly affixing a further    element to the construction object—instead of or in addition to the    “dowel” function.-   Expansion of the liquefied thermoplastic material into a cavity, for    example of a brick, such as a vertically perforated brick, or a    cavity behind a panel like or plank like construction object.

The embodiments described referring to FIGS. 1-2 and 4-6 are all basedon the—in many cases advantageous—principle according to which thevibrations are coupled into the anchoring element from the rear side andthe necessary force is coupled into the sonotrode as a tensile force(pulling force). Even in applications of this principle, it is possibleto choose whether the sonotrode or the counter element or both move tocompress the anchoring element that is being partly liquefied. This isillustrated in FIGS. 7 a, 7 b, 8 a, and 8 b.

FIG. 7 a shows the arrangement—for illustration purposes, theconstruction object is shown to have a through opening (theconsiderations referring to this Figure also apply to blind holes), andthe sonotrode is illustrated to be of the type remaining in place afteranchoring and being part of the anchor—at the onset of the anchoringprocess. Similar to the process described referring to FIGS. 5 a through5 e, the anchoring process features a pulling motion of the sonotrode 3.In the figures, also structures 3.11 of the sonotrode for affixing thesame to the vibration generating device—are shown. FIG. 7 b illustratesthe anchor—being made up of the anchoring element 1 and of the sonotrode3 remaining in place—after anchoring. As illustrated, in thisembodiment, the front surface 1.12 of the anchoring element remainsunaffected by the anchoring process.

An other basic possibility is shown in FIGS. 8 a and 8 b illustrating ananchoring arrangement at the onset of the anchoring process and theanchor after the anchoring process. In the illustrated example, theopening is a blind hole, but the same process also applies to throughopenings. During the anchoring process, the pulling force 4 acting onthe anchoring element 1 serves to hold the anchoring element still,whereas the counter element 2 is pushed towards the rear end of theanchoring element. The mechanism is basically the same as the oneillustrated in FIGS. 7 a, 7 b, but the “pushing the counter element”variant is especially suitable for blind holes of limited depth.

A further advantage of the approach according to the invention is—asmentioned above—the suitability for automated anchoring, for example ina manufacturing line of furniture or pre-fabricated building elements orother objects, or also by a handheld device. An according methodfeatures the step of automatically applying the force on the sonotrodeand on the counter element (or rather, between the sonotrode or an itemconnected thereto and the counter element). For example, a springelement may be present between the sonotrode and the counter element.The according method is illustrated in FIGS. 9 a through 9 e. While inthe illustration, the arrangement is of the kind described referring toFIGS. 4 and 5 a-5 e, the described principle also applies to otherarrangements, for example with a sonotrode as shown in FIG. 1 with arear broadening 3.2.

FIG. 9 a illustrates the step of inserting the sonotrode with theanchoring element and the base element in the opening. In addition tothe elements described referring to FIG. 5 a, the arrangement furthercomprises a spring element 34 under tension between the sonotrode (ormore precisely, a casing or the like that is connected to the sonotrodebut vibratory de-coupled from it such as the vibration generatingdevice's 32 casing or, as in the drawing, a frame 33 or other objectattached to it) and the counter element 2. After the positioning of theassembly, the spring force may be released. As illustrated by the doublearrows 35 shown in FIG. 9 b, both the force onto the sonotrode 3 and thecounter force onto the counter element 2 may then be exerted by thespring element. Since during the anchoring process, the vibrationgenerating device 32 has an at least approximately unchanged position,the spring force will cause the counter element 2 to move forward duringanchoring, as illustrated in FIG. 9 c. Since the liquefaction primarilytakes place at and around the interface between the base element 31 andthe anchoring element 1, there will not be any liquidized thermoplasticmaterial at the interface between the anchoring element 1 and thecounter element 2, and the counter element may—as in the previousembodiments—be removed together with the sonotrode (FIG. 9 d) afteranchoring. FIG. 9 e shows the anchor after the process.

In the illustrated configuration, the spring element is shown to abut aseparate, sleeve or ring shaped counter element 2. This is notnecessarily the case. Rather, a (for example ring shaped) abutment faceof the spring element itself may serve as the counter element instead.Instead of a spring element—that has been pictured in the Figures forillustration purposes—in a load frame also other mechanisms for applyinga force may be used such as a hydraulic element, a pneumatic elementetc.

The method according to the invention is especially suited for affixingan anchor to a weak or brittle porous material. It is moreover suitedfor anchoring in objects with no or only very weak material behind athin, hard wall. Such objects may for example be hollow walls or hollowcore boards etc.

FIGS. 10 a and 10 b show the anchoring in a construction object 11,where the construction object is a hollow core board 11. In the shownembodiment, the hollow core board comprises two comparably thin and hardpanels 51 and a soft filling material 52 therebetween. The fillingmaterial may for example be a core or isolation material such aspolystyrene foam or glass wool etc.

The anchoring takes place by a process as for example describedreferring to FIGS. 1 and 2 (with or without automatically applying theforce as illustrated in FIG. 9). The anchoring, especially the securingagainst pulling forces, is takes place irrespective of properties of thefilling material and even works if no filling material is present atall. If, however, the filling material 52 has some stiffness andporosity, the anchoring is even more effective than for a completelyhollow filling space.

The anchoring in a hollow wall is illustrated in FIGS. 11 a and 11 b.The object 11 is a plank (or a wall made of a plurality of planks orother flat objects) attached, by means of distance holders, in front ofa wall 61 that may be made of very hard material such as hard concrete.The anchoring method may be any one of the above-described methods. Theliquefied thermoplastic material expands into the cavity behind theplanks—as illustrated in FIG. 11 b—and reliably secures the anchor (thatcomprises the anchoring element 1 as well as the sonotrode 3),especially against pulling forces.

FIGS. 11 a and 11 b are also a further illustration of excerting theforce between the sonotrode and the counter element by means of a springelement, here comprising two springs guided by appropriate guiding means38. In this example, in contrast to the example of FIG. 9, the springcauses the sonotrode 3 to retract while the counter element 2 restsagainst the front surface of the construction object. If the methodillustrated in FIGS. 11 a and 11 b is carried out by a hand held tool,the tool may comprise an outer casing in which the vibration generatingdevice 32 is translationally movable, so that the outer casing held bythe user keeps its position during the process, whereas the vibrationgenerating device retracts inside the outer casing. The outer casing mayfor example be connected to the counter element 2.

FIGS. 12 a and 12 b illustrate the anchoring in a vertically perforatedbrick 11, where expansion of the liquefied polymer material (FIG. 12 b)takes place into the cavities 11.3 of the brick. The bore in this caseis rectangular or at an angle to the vertical perforation and opens outto the vertical perforation.

All of the above described embodiments except the one of FIG. 3 arebased on the—in many cases advantageous—principle according to which thevibrations are coupled into the anchoring element from the rear side andthe necessary force is coupled into the sonotrode as pulling force—the“backward” anchoring. In these embodiments, a shaft 3.4 of the sonotrodein some way has to reach through the anchoring element. The so fardescribed, preferred embodiment is to form the anchoring element in atube or sleeve shape and have the shaft of the sonotrode reach throughits central opening. The outer diameter of the sonotrode shaft 3.4 isalways smaller than the inner diameter of the anchoring element 1.This—preferred—configuration is illustrated in FIG. 13 a, which shows asection through the sonotrode shaft and anchoring element. However, sucha symmetrical configuration is not a necessity. Rather, also otherconfigurations, such as the eccentric set-up shown in FIG. 13 b or otherconfigurations (with or without circular symmetry of the outer contour)are possible. FIG. 13 c shows yet a configuration where the anchoringelement comprises two separate anchoring element pieces 1.1, 1.2arranged at different sides of the sonotrode 3. This makes aT-bar-shaped sonotrode shaft possible, which is advantageous in view ofthe mechanical stability. The place where the counter element 2 would belocated is also illustrated in the FIG. 13 c.

In FIGS. 13 a-13 c—as well as FIGS. 16-18, the axis 7 would beperpendicular to the drawing plane.

In embodiments based on the “backward anchoring” principle, the force 4to be coupled into the anchoring element acts a tensile force on thesonotrode 3. This requires an appropriate coupling means on thevibration generating device, which does not only need to be suitable fortensile loading but also for the transmission of mechanical vibrationswhile under tensile loading. Such coupling means are known to oneskilled in the art. They are often based on a form fit (screw joints,snap fastenings, bayonet catches, etc.) or possibly a material fit(glued, welded or soldered connections) or a friction fit (clampedconnections). Such generally known coupling means are not furtherdiscussed here. The principle of a form-fit coupling means is shown inFIG. 14. This coupling can be used as shown or in an alternative form.The vibration generating device comprises an extension protruding into aclearance at the proximal end of the tool 3 and widening towards itsdistal end so that it can transmit a tensile force. For coupling thetool 3 to the vibration generating device, these are moved perpendicularto the plane of FIG. 14 relative to each other. Dovetails or similarmodifications may be considered.

In embodiments where the sonotrode remains in place and forms a part ofthe anchor after anchoring, the same coupling means may also be used tocouple a further element to the anchor (of course, in these embodimentsan essentially irreversible coupling of the sonotrode to the vibrationgenerating device—such as gluing, welding soldering or the like—is notwell suited)

FIG. 15 shows a further embodiment of a method and device according tothe invention. This embodiment is based on the concept illustratedreferring to FIGS. 1 and 2, but with the substantial difference that theanchoring element is configured so that the liquefaction of thethermoplastic material starts at the interface between the anchoringelement 1 and the counter element 2 and not at the interface between theanchoring element 1 and the sonotrode 3, as in the embodiments of FIGS.1 and 2. To this end, the anchoring element comprises energy directorsin contact with the interface to the counter element. In the illustratedembodiment, the energy directors are constituted by a taper towards thefore side of the anchoring element. The counter element slightlyprotrudes into the opening of the construction object so that thethermplastic material that flows sidewards after liquefaction does notooze out of the opening but protrudes into the pores/structures of theconstruction material.

This embodiment is especially suited for situations where anchoring at apre-defined position in the opening and/or close to the front side ofthe construction object 11 is desired.

FIG. 16 and show variants of sonotrode properties that may be used forarrangements/methods of the “rearward” type in accordance with thepresent teaching. The sonotrode of FIG. 16 comprises a plurality ofliquid guiding channels 3.21 that are for example provided as grooves inthe forward facing surface of the rear broadening (FIG. 16 shows a viewonto this surface facing towards the user/apparatus applying themethod). The material of the anchoring element will liquefy in contactwith the foremost surface of the rear broadening 3.2 and then can evadeinto the channels and from there towards the lateral sides. Thisembodiment, among other things, is suitable to concentrate the liquefiedmaterial to certain azimuth angles.

In the embodiment of FIG. 17, the rear broadening comprises openings orinterruptions 3.22 allowing the liquefied material to pass through. Dueto this concept, rather than causing the anchoring element to becomeever shorter during the anchoring process by being confined between thesonotrode rear broadening and the counter element, the sonotrode ispartly moved through anchoring element material, leaving a cushion ofsuch material on the rear side of the sonotrode. This embodiment isespecially suited for situations, where the anchoring is to bear axial,rearward facing loads as well, as the cushion can absorb such forces,especially if it fills the space between the rear broadening and thebase of the opening in the construction object.

Instead of the illustrated interruptions directed radially outward,other kinds of openings/interruptions may be present. For example, therear broadening may comprise a plurality of holes of same or differentsizes. As an example, such openings may be arranged in radially directedrays and comprise sizes that increase with increasing distance from theshaft 3.4.

Further examples of “forward” type devices and methods are describedreferring to FIGS. 18-21.

FIG. 18 shows a sectional view of an arrangement of an anchoring element1 and a counter element 2. In contrast to the embodiment illustrated inFIG. 3, the portion of the counter element reaching trough the anchoringelement 1 is arranged at the periphery of the anchoring element. In theillustrated configuration, it comprises two rods 2.4 guided sidewaysalong the length of the anchoring element. This configuration—and otherconfigurations with counter elements hold from the outer circumferencerather than from the core of the anchoring element—may have advantagesin handling the counter element and the sonotrode/vibration generatingdevice, compared to the embodiment of FIG. 3.

FIGS. 19 a and 19 b show a first example of a device and method, wherethe counter element 2 is formed as a receptacle such as a sleeve. FIG.19 a shows the arrangement at the onset of the anchoring process,whereas FIG. 19 b shows the arrangement towards the end of the anchoringprocess.

The receptacle comprises a single outward facing mouth 2.2 and aplurality of openings 2.1 in the lateral surface (on the side) andpossibly also in the inward facing surface (not shown). The anchoringelement 1 may, prior to the anchoring process, be present in thereceptacle and for example be fix in it. As an alternative, theanchoring element may initially be separated from the receptacle andinserted in it prior to anchoring.

In the anchoring process, the sonotrode 3 presses against the anchoringelement from the front side while it vibrates (mechanical vibrations 5).The counter element comprises a flange 2.3 that rests on the outersurface of the construction object in vicinity to the opening and thuscauses the counter force 6 to be created as a normal force acting on theflange 2.3. Due to the effect of the mechanical vibrations and thepressing force applied to the anchoring element, the anchoring elementstarts melting and thereafter is pressed through the openings 2.1 intopores of the surrounding material 52 that may be substantially lessmechanically stable than the front panel 51 that creates the normalforce (FIG. 19 b). In order for the thermoplastic material to startmelting in vicinity of pores, either the receptacle 2 or the anchoringelement 1 or both comprise according energy directing structures such asnarrowings, edges, tips etc. In the depicted configuration, theanchoring element comprises inward facing protrusions 2.4 in vicinity tothe openings 2.1.

The embodiment of FIGS. 19 a and 19 b may for example also be used inconnection with an anchoring element material that is softer thananchoring element materials of other embodiments, so that the heat formelting the material may also, predominantly or in a substantialproportion, be created by internal friction instead of predominantly byabsorption of mechanical energy at interfaces.

The sleeve like receptacle anchored in the for example relatively softand/or brittle material may for example be used as a dowel. It may evencomprise pre-fabricated structures—such as a threading—to affix afurther element, such as a screw, to it. Such a further element can bearupon the sleeve itself and/or remaining thermoplastic material insidethe sleeve.

In addition or as an alternative, the flange 2.3 may be used—like a headof a screw—to affix an other element—placed before anchoring—to thefront surface.

In the shown configuration, the counter force is created, by means of aflange, as a normal force. However, the sleeve like counter element 2could equally well be held by other means—for example actively by theuser/apparatus carrying out the method.

Even though in the shown configuration the counter force is created asnormal force and thus ultimately the force necessary for anchoring restson the object, there is a substantial advantage over the prior artmethod for example described in WO 98/00109: The surface comprising thestructures/pores and/or cavities into which the liquefied thermoplasticmaterial ultimately penetrates itself is not mechanically loaded. Theplace at which the normal force is created—the front panel in the shownconfiguration—is not identical with the place in which the anchoringelement ultimately is anchored. This advantage is useful inconfigurations where there is not enough mechanically strong material inthe construction object but the anchoring element has to be anchored inmechanically less stable material—such as the illustrated constructionobject comprising a thin, hard panel, and softer material underneath,i.e. a sandwich or isolation material.

FIGS. 20 a and 20 b show yet an other embodiment of a device/methodwhere the counter element is formed as a sleeve like receptacle. In thisembodiment, however, the counter force 6 is created by the normal forceat the base of the blind bore in the construction element 11, i.e. bythe counter element being pressed against the base of the blind hole.This embodiment is suitable for construction objects that are comparablystiff and mechanically stable, such as construction objects of wood orwood composites or (porous) concrete or dense metal foams etc.

The embodiment of FIGS. 20 a and 20 b is among other things, especiallysuited for forming a dowel for a further element 22, where theconnection to the further element has to bear heavy loads and/or loadsfor a long time. State of the art dowels based on polymer materialsfeature the problem that polymer material flows over a long time. Thisproblem is significantly reduced due to the effect of the—for examplemetallic—sleeve 2, to which the further element may be affixed. Forexample, as illustrated in FIG. 20 b showing the anchoring element afterthe anchoring process, the sonotrode may be chosen to displacesubstantially all polymer material over a substantial portion of thedepth of the sleeve, so that the further element 22—illustrated is ascrew—is directly secured to the sleeve 2.

The variant of a device illustrated in FIG. 21 is distinct from thepreviously shown embodiments in that it comprises openings 2.1 also (oronly) at the base of the sleeve. An energy director assuring melting ofthe thermoplastic material at the base is formed by a rearwardly facingprotrusion 2.11 at the base of the sleeve. This variant could also beprovided with a flange feature like the embodiment of FIG. 19 a.

Various other embodiments may be envisaged without departing from thescope and spirit of the invention.

1.-25. (canceled)
 26. A device for producing an anchor in a constructionmaterial object, the device comprising: an anchoring element comprisingthermoplastic material and comprising a proximally facing coupling faceand a distally facing coupling face, a counter element comprising acounter element coupling face, and a vibration element, the vibrationelement extending between a proximal fore end and a distal rear end andhaving a vibration element shaft portion and a vibration element footportion, the vibration element foot portion secured to a distal sectionof the shaft portion and forming a proximally facing outcoupling face, aproximal section of the shaft portion being equipped for being coupledto a generator of mechanical vibrations, the shaft portion being capableof transferring the mechanical vibrations in a distal direction to thefoot portion, wherein the anchoring element, the counter element and thevibration element are arranged or configured to be arranged so that theoutcoupling face of the vibration element is in contact with thedistally facing coupling face of the anchoring element and the counterelement coupling face is in contact with the proximally facing couplingface, whereby the anchoring element is capable of being clamped betweenthe vibration element and the counter element by applying a pullingforce to the vibration element shaft portion and simultaneously applyinga pushing force of equal magnitude and opposite direction to the counterelement, wherein a lateral outermost surface portion of the anchoringelement is formed by the thermoplastic material, whereby portions of thethermoplastic material are liquefiable by the joint application of thepulling force, the pushing force and mechanical vibrations coupled intothe vibration element and pressable into structures of the constructionmaterial object adjacent the lateral outermost surface portion to yield,after re-solidification, an anchoring in the construction materialobject.
 27. The device according to claim 26, further comprising thevibration generator.
 28. The device according to claim 26, wherein theanchoring element consists of the thermoplastic material.
 29. The deviceaccording to claim 26, further comprising an automated mechanism forsimultaneously applying the force and the counter force.
 30. The deviceaccording to claim 29, wherein the automated mechanism comprises aspring element.
 31. The device according to claim 26, wherein theanchoring element comprises a plurality of initially separated orinitially weakly coupled parts.
 32. The device according to claim 26,wherein the anchoring element is tube shaped, having an axiallyextending through opening, and wherein the shaft portion extends throughthe axially extending through opening.
 33. The device according to claim32, wherein the counter element has a counter element through opening,and wherein the shaft portion extends through the counter elementthrough opening.
 34. The device according to claim 26, wherein thelateral outermost surface portion is near an interface between theoutcoupling face and the distally facing coupling face or near aninterface between the counter element coupling face and the proximallyfacing coupling face or comprises both, portions near an interfacebetween the outcoupling face and the distally facing coupling face andportions near an interface between the counter element coupling face andthe proximally facing coupling face.
 35. A device for producing ananchor in a construction material object, the device comprising: ananchoring element comprising thermoplastic material and comprising aproximally facing coupling face and a distally facing coupling face, acounter element, the counter element extending between a proximal foreend and a distal rear end and having a counter element shaft portion anda counter element foot portion, the counter element foot portion securedto a distal section of the shaft portion and forming a proximally facingcounter element coupling face, and a vibration element, a proximalsection of the vibration element being equipped for being coupled to agenerator of mechanical vibrations, the vibration element being capableof transferring the mechanical vibrations in a distal direction to adistally facing outcoupling face, wherein the anchoring element, thecounter element and the vibration element are arranged or configured tobe arranged so that the outcoupling face is in contact with theproximally facing coupling face of the anchoring element and the counterelement coupling face is in contact with the distally facing couplingface, whereby the anchoring element is capable of being clamped betweenthe vibration element and the counter element by applying a pushingforce to the vibration element and simultaneously applying a counterforce of equal magnitude and opposite direction to the counter elementshaft portion, wherein a lateral outermost surface portion of theanchoring is formed by the thermoplastic material, whereby portions ofthe thermoplastic material are liquefiable by the joint application ofthe pulling force, the counter force and mechanical vibrations coupledinto the vibration element and pressable into structures of theconstruction material object adjacent the lateral outermost surface toyield, after re-solidification, an anchoring in the constructionmaterial object.
 36. The device according to claim 35, furthercomprising the vibration generator.
 37. The device according to claim35, wherein the anchoring element consists of the thermoplasticmaterial.
 38. The device according to claim 35, further comprising anautomated mechanism for simultaneously applying the force and thecounter force.
 39. The device according to claim 38, wherein theautomated mechanism comprises a spring element.
 40. The device accordingto claim 35, wherein the anchoring element comprises a plurality ofinitially separated or initially weakly coupled parts.
 41. The deviceaccording to claim 35, wherein the anchoring element is tube shaped,having an axially extending through opening, and wherein the shaftportion extends through the axially extending through opening.
 42. Thedevice according to claim 35, wherein the lateral outermost surfaceportion is near an interface between the outcoupling face and theproximally facing coupling face or near an interface between the counterelement coupling face and the distally facing coupling face or comprisesboth, portions near an interface between the outcoupling face and theproximally facing coupling face and portions near an interface betweenthe counter element coupling face and the distally facing coupling face.43. A device for producing an anchor in a construction material object,the device comprising: a sleeve element, the sleeve element comprising alateral wall portion with a proximally facing mouth and a distal endportion, whereby the sleeve element forms a receptacle, the wall portionextending distally from the mouth, the sleeve element comprising aplurality of openings, an anchoring element comprising thermoplasticmaterial and comprising a proximally facing coupling face, and avibration element, a proximal section of the vibration element beingequipped for being coupled to a generator of mechanical vibrations, thevibration element being capable of transferring the mechanicalvibrations in a distal direction to a distally facing outcoupling face,wherein the anchoring element, the counter element and the vibrationelement are arranged or configured to be arranged so that anchoringelement is at least partially inserted into the receptacle formed by thesleeve element through the mouth, and the outcoupling face is in contactwith the proximally facing coupling face of the anchoring element,whereby the anchoring element is compressible between the vibrationelement and the sleeve element by applying a pushing force to thevibration element and simultaneously applying a counter force of equalmagnitude and opposite direction to the sleeve element, whereby portionsof the thermoplastic material are liquefiable by the joint applicationof the pulling force, the counter force and mechanical vibrationscoupled into the vibration element and pressable through the openingsinto structures of the construction material object adjacent the sleeveelement to yield, after re-solidification, an anchoring in theconstruction material object.
 44. The device according to claim 43,further comprising the vibration generator.
 45. The device according toclaim 43, wherein the sleeve element comprises a flange configured torest on an outer surface of the construction object so as to cause thecounter force as a normal force.
 46. The device according to claim 43,wherein the sleeve element comprises at least one energy director. 47.The device according to claim 43, wherein the anchoring element consistsof the thermoplastic material.
 48. The device according to claim 43,wherein at least a distal portion of the vibration element is shaped tobe introduced into the receptacle formed by the sleeve element throughthe mouth.